The present invention relates to fabrics, yarns and processes for making yarns. In particular, the present invention relates to yarns having an internal core encased in an outer fiber, and a process of spinning fibers about a core to form yarns displaying desirable performance characteristics, such as enhanced strength and cut-resistance.
It has been known in the textile field to combine certain fibers and filaments to form yarns and fabrics with enhanced physical properties, such as cut-resistance, strength and fire-resistance.
These yarns may be referred to as high performance yarns due to the physical properties expected from them. Conventional high performance yarns generally include cores, formed from one or more fibers, wrapped with one or more additional fibers. Materials used to form the cores of known high-performance yarns have included, among others, certain glasses, metals and polymeric materials. Likewise, known wrapping fibers generally include certain metals and polymeric materials. Unfortunately, most of these conventional high performance yarns fail to exhibit the optimum combination of economy and performance necessary to make them both useful and cost efficient. Due to the nature of the materials used in conventional high performance yarns and the performance characteristics expected therefrom, these yarns often suffer from time-consuming production methods and less than optimum performance characteristics. Consequently, there is a continuing need for alternative high performance yarns and fabrics.
Furthermore, it is known in the knitting industry that an unbalanced yarn, or a yarn with a high degree of twist, will cause torqueing in a finished fabric. As a result of this phenomenon, yarns having a low degree of twist, usually in the range of about 2.4 to about 3.5 twist multiple, typically are used in knitted fabrics. Conventional spinning processes also generally impart a clockwise, or Z direction, twist to a yarn. As a result, if a Z twist yarn having a high twist multiple, was incorporated into a knitted fabric product such as a glove, then the fingers of the glove would tend to torque in a clockwise, or Z, direction. When the use of high twist multiple yarns is necessary or cannot be avoided, conventional methods of avoiding such unwanted torqueing of the finished fabric include producing balanced yarns by bundling two or more Z twist yarns together and then twisting the bundles in the S direction to a balanced state. Since high performance yarns are often incorporated into garments, such as gloves, wherein torqueing would adversely affect not only the appearance but also the performance of the garment, it is desirable to provide a high performance yarn that tends not to cause torqueing in the garment in which it is incorporated.
The present invention includes, among other aspects, yarns and fabrics exhibiting enhanced performance characteristics, such as cut-resistance, and methods of making such yarns. The yarns of the present invention include an inner core with a sheath applied thereto. The yarn cores of the present invention may be formed from one or more filaments or fibers containing materials that impart desired performance characteristics and/or economy to the overall yarn. Likewise, the yarn sheathes of the present invention also may be formed from one or more fibers containing materials that impart desired performance and/or economy to the yarn The fibers or filaments forming the core and/or the sheath may be processed, such as by roughening and/or stretch-breaking and/or S twisting, in order to improve the performance of the final yarn or fabric.
One embodiment of the present invention includes a yarn having both a core that includes one or more glass filaments contacted with one or more metal filaments and a sheath applied to the core. The sheath will include a series of fibers wrapped about the core. The glass or other synthetic material filaments of the core may be either roughened and/or stretch-broken. Roughening of the glass filaments increases the coefficient of friction for any such filaments, thereby reducing the likelihood that the sheath fibers or filaments combined therewith will slide along the core, but instead will tend to be engaged or gripped by the core to reduce risk of gaps and exposure of the core. Stretch-breaking of a fiber or filament tends to enhance both the cut-resistance and feel of the fabric into which it is incorporated. The sheath fibers that are wrapped about the core may also be stretch-broken, and may include various types of polymeric fibers, carbon-based fibers, or fibers having metallic properties or characteristics selected in order to impart the desired performance characteristics to the resultant fabric formed from the yarn.
Another embodiment of the present invention includes a yarn having a core formed of one or more roughened or pitted metal filaments contacted with one or more other synthetic filaments and a sheath applied to the core. The synthetic filaments included in the core can provide improved static dissipation properties and may also be roughened and/or stretch-broken.
Methods of forming yarns of the present invention are also provided. One embodiment of the method of the present invention includes contacting a glass filament with a metal filament to form a core and wrapping the core with a sheath formed of one or more fibers. The method of producing yarns may also include roughening at least the glass filament of the core. Additional fibers, including carbon-based fibers and/or various polymeric fibers may be contacted with at least one of the glass filament and the metal filament in the core. Such additional fibers may also be stretch-broken and/or roughened and as an additional step, at least a portion of the yarn also can be melted. This melting of at least a portion of the composite yarn generally can generate a consolidated mass within the yarn by transforming one or more of the yarn fibers into an amorphous mass that may partially coat other fibers of the yarn.
In another embodiment of the method of forming yarns of the present invention includes contacting a metal filament with a synthetic fiber to form the yarn core, and wrapping the core with a sheath formed of one or more fibers. As with the above methods and alternatives, one or more filaments or fibers of the core and sheath of the yarn may be roughened, stretch-broken, and/or twisted in the S direction in order to provide desired performance characteristics.
In still a further embodiment, the composite high performance yarn of the present invention is formed from multiple plies including a first ply with a glass filament core, a second ply with a metal filament core and an additional ply. The additional or third ply can include a material such as an aramid, para-aramid, high density polyethylene, polypropylene, polyester, polyamide or other high performance polymeric material or can be formed from a natural or synthetic filler material. The multiple plies are each wrapped with a series of sheath fibers and then twisted together, typically with an S-twist, to form a multi-ply core. Alternatively, a first ply having a combined glass and metal core can be combined with a high performance, cut resistant filament or a filler filament, or both with each core yarn wrapped with a protective sheath and then twisted to form a yarn bundle. These and other of the aforementioned aspects of the methods of forming yarns may be incorporated herein.
These and other features, aspects, and advantages of the present invention will become more apparent upon review of the detailed description set forth below when taken in conjunction with the accompanying drawing figures, which are briefly described as follows.